Size and shape evolution of highly magnetic iron nanoparticles from successive growth reactions.

We present a synthetic protocol for the solution-phase synthesis of monocrystalline, metallic iron nanoparticles based on seed-mediated growth, showing near-single nanometre control over particle size. A shape evolution to cubic nanoparticles is also observed with increasing size. Magnetic properties were measured after surface oxidation, showing the potential of our protocol to tune the magnetism of iron nanoparticles for applications requiring superparamagnetic or ferromagnetic nanoparticles.

Role of Surface Capping Molecule Polarity on the Optical Properties of Solution Synthesized Germanium Nanocrystals.

The role surface capping molecules play in dictating the optical properties of semiconductor nanocrystals (NCs) is becoming increasingly evident. In this paper the role of surface capping molecule polarity on the optical properties of germanium NCs (Ge NCs) is explored. Capping molecules are split into two groups: nonpolar and polar. The NCs are fully characterized structurally and optically to establish the link between observed optical properties and surface capping molecules. Ge NC optical properties altered by surface capping molecule polarity include emission maximum, emission lifetime, quantum yield, and Stokes shift. For Ge NCs, this work also allows rational tuning of their optical properties through changes to surface capping molecule polarity, leading to improvements in emerging Ge based bioimaging and optoelectronic devices.

How much is '5-a-day'? A qualitative investigation into consumer understanding of fruit and vegetable intake guidelines.

BACKGROUND: Despite the known health benefits of fruit and vegetables (FV), population intakes remain low. One potential contributing factor may be a lack of understanding surrounding recommended intakes. The present study aimed to explore the understanding of FV intake guidelines among a sample of low FV consumers. METHODS: Six semi-structured focus groups were held with low FV consumers (n = 28, age range 19-55 years). Focus groups were recorded digitally, transcribed verbatim and analysed thematically using nvivo (QSR International, Melbourne, Australia) to manage the coded data. Participants also completed a short questionnaire assessing knowledge on FV intake guidelines. Descriptive statistics were used to analyse responses. RESULTS: The discussions highlighted that, although participants were aware of FV intake guidelines, they lacked clarity with regard to the meaning of the '5-a-day' message, including what foods are included in the guideline, as well as what constitutes a portion of FV. There was also a sense of confusion surrounding the concept of achieving variety with regard to FV intake. The sample highlighted a lack of previous education on FV portion sizes and put forward suggestions for improving knowledge, including increased information on food packaging and through health campaigns. Questionnaire findings were generally congruent with the qualitative findings, showing high awareness of the '5-a-day' message but a lack of knowledge surrounding FV portion sizes. CONCLUSIONS: Future public health campaigns should consider how best to address the gaps in knowledge identified in the present study, and incorporate evaluations that will allow the impact of future initiatives on knowledge, and ultimately behaviour, to be investigated.

Injection-seeded, single-frequency, q-switched erbium:glass laser for remote sensing.

We have built and characterized an injection-seeded, Q-switched, flash-lamp-pumped, eye-safe Er:glass laser that is suitable for coherent remote sensing. The output of the device is a 400-ns, single-frequency, transform-limited pulse of 1 mJ at 1.552 mum.

Microscopic study of normal parietal pericardium and unimplanted Puig-Zerbini pericardial valvular heterografts.

This investigation used light microscopy and transmission and scanning electron microscopy to study native human and bovine parietal pericardium, glutaraldehyde-fixed bovine pericardial patch-grafts, and bovine pericardial cusps of unimplanted Incor or Puig - Zerbini heart valves. The primary objective was to obtain a data base for the future evaluation of postimplantation structural alteration in this valve and in other cardiac valvular bioprostheses constructed of pericardium. The mesothelial cell layer in normal pericardium was best preserved in the bovine tissue. In both bovine patch-grafts and Puig - Zerbini valvular cusps, the serosal surface usually was completely devoid of mesothelial cells and revealed an underlying, finely fibrillar basal lamina. The fibrosa varied in thickness and organization, both within and between the two species, but similar nervous, vascular, and connective tissue components were observed in each. The epipericardial surface was smoother, had fewer elastic fibers, and possessed more surface cells in the human tissue than in the bovine tissue. No evidence of significant tissue degeneration or remodeling was noted in either the stored patch-grafts or heart valves when compared with control bovine and human pericardial tissue layers.

Morphological alterations in dura mater encephali used as ventricular wall grafts in the canine heart.

Structural changes within homologous dura mater patch-grafts surgically implanted in the right ventricular wall of the heart were studied in nine adult dogs utilizing light microscopy and transmission and scanning electron microscopy. Physical examination of the dogs after surgery presented no clinical signs of abnormalities caused by either the surgery or the nature of the graft. After one week of implantation, a fibrous organization extending from the wound margins over the entire graft greatly increased its thickness. In addition, it was observed that (1) an increase in cellularity, vascularity and connective tissue elements occurred on the external surface of the patch-graft, (2) these same changes occurred regardless of which surface (periosteal or arachnoidal) was used as the external or pericardial surface, (3) the graft core underwent a transition from a relatively acellular and avascular connective tissue structure into one that was heavily infiltrated by a variety of cellular elements and new blood vessels, and (4) these morphological changes were interpreted as an attempt to incorporate the graft into the host tissue, resulting in an increase in both viability and stability of the graft. These findings indicate that homologous dura mater is a suitable material for use in the surgical repair of the cardiac wall.

Study of the periosteal and arachnoidal aspects of dura mater implanted surgically in the ventricular wall of the canine heart.

After surgical removal of a portion of the cardiac wall, homologous dura mater cardiac grafts were sutured to the margins of the incision in the sternocostal wall of the right ventricle of the canine heart and recovered after 1, 4, 6 and 8 weeks of implantation. Representative tissue specimens were processed for and studied by means of SEM and TEM. The primary objectives were to study morphological changes in the dura mater grafts used to repair the lesions or defects in the cardiac wall and to compare alterations in the periosteal and arachnoidal aspects of the dura mater grafts after being implanted for varying periods of time. After one week of implantation, an amorphous layer of fibrin was deposited on or near the luminal surface of the original dura mater grafts. At four weeks of grafts implantation, a 'remodeling' process was apparent below the luminal surface of the graft. Although a large accumulation of fibrin was still present at this time, there was also an increase in the number of cellular and fibrillar components within the implant. Large numbers of macrophages and active fibroblasts were visible at this time along with new collagen. At the sixth week of implantation, an abundance of active fibroblasts, the presence of normal collagen and a darkly staining material interpreted as recently synthesized connective tissue components, fibrin deposits and/or degenerating collagen were also observed. Phagocytosis of the remaining fibrin was noted during this period indicating a continuation of the remodeling process at the luminal surface. Finally, after eight weeks of implantation, it was revealed that the original densely woven and relatively acellular graft had become infiltrated with various blood cells and vascular channels.